Embodiments of the present invention relate to a substrate cleaning chamber, chamber components, and substrate cleaning method.
In the manufacture of integrated circuits and displays, a substrate such as a semiconductor wafer or display, is placed in a process chamber and processing conditions are set to form various active and passive features on the substrate. Advanced integrated circuits and displays use multiple levels of sub-micron sized interconnects to connect the features formed on a substrate. In order to improve circuit reliability, the surface features on the substrate are cleaned prior to the deposition of overlying materials on the surfaces of the interconnect or other features. A typical pre-clean or cleaning chamber comprises an enclosure around a process zone which contains chamber components that include a substrate support to hold the substrate, a gas supply to provide a cleaning gas, a gas energizer to energize the cleaning gas to etch away the surface of the features to clean the substrate, and a gas exhaust to remove spent gas, as for example, described in U.S. Pat. No. 6,107,192, issued on Aug. 22, 2000, to Subrahmanyan et al., which is incorporated by reference herein and in its entirety.
However, conventional pre-clean chambers and processes often do not uniformly clean the surfaces of the ever smaller features being fabricated on a substrate. Failure to properly clean these features can result in void formation or increased electrical resistance between the surface features. For example, a layer of native oxides and contaminants which are left on the features can cause void formation by promoting the uneven distribution of material deposited on the substrate in a subsequent processing step, or by causing the corners of the features to grow, merge, and seal off before the feature is filled with the material being deposited therein. Pre-cleaning processes are especially desirable to uniformly etch and clean substrate surfaces for subsequent barrier layer or metal deposition processes.
It is also desirable to have pre-clean chamber that can receive ever increasing amounts of accumulated deposits without causing the chamber components to stick to each other or the accumulated deposits flaking off between cleaning cycles. During the etch cleaning process, cleaning residues often deposit on the exposed internal surfaces in the chamber. Build-up of these residues is undesirable as the accumulated deposits can flake off when thermally stressed to fall upon and contaminate the substrate and other chamber surfaces. Periodic cleaning of the residues off the chamber components reduces this problem but also requires disassembly and cleaning of the chamber components and shut-down of the chamber. Further, when metal-containing process residues accumulate on the ceiling of a chamber having an external inductor coil gas energizer to couple induction energy through the ceiling to energize the cleaning gas, the metal containing residues reduce or prevent coupling of the induction energy through the ceiling. Conventional cleaning chambers use a process kit comprising lower and upper shields, and various deposition or cover rings arranged about the substrate support to receive such process residues. Periodically, the process kit components are dismantled and removed from the chamber for cleaning. However, it is desirable to have a chamber and internal components which can receive ever larger amounts of accumulated deposits so that the chamber can be used for a larger number of process cycles before shut down.